Dual-crosslinked alginate hydrogels with a high Ca2+ content were successfully prepared, which extended their properties, and showed potential application as a skin strain sensor.

Core-shell nanoparticles composed of a nonnoble metal core and a noble metal shell are of great significance in many areas including chemical catalysis, optical detection, and magnetic separation. Through a modification of the commonly used polyol process, Ni@Pt core-shell nanoparticles that are less than 10 nm in total size and have a very thin Pt shell can be fabricated by a sequential reduction approach. The prepared core-shell nanoparticles were characterized with TEM, XRD, molecular dynamics (MD) simulations, and electrochemical method. It was found that these core-shell particles exhibit the structural characteristics of fcc Ni nanocrystals with a slightly expanded lattice constant but the electrochemical properties of a Pt surface with a significantly shortened Pt-Pt interatomic distance than for pure Pt nanoparticles. The structural characteristics of the prepared core-shell particles revealed by the TEM, XRD, and electrochemical analyses were well verified by MD simulations of a Ni@Pt core-shell particle with a monolayer Pt shell. It is believed that the prepared Ni@Pt core-shell nanoparticles could be promising cathode catalysts in PEM fuel cells with much reduced Pt content but significantly increased catalytic activity.

By using a catalyst-lean thin-film RDE method, the fast kinetics of the hydrogen oxidation reaction (HOR) on highly dispersed Pt nanoparticle electrocatalysts can be determined, free from the interference of the mass transport of H(2) molecules in solution. Measurements with carbon-supported Pt nanoparticles of different sizes thus allow revealing the particle size effect of Pt for the HOR. It is shown that there is a "negative" particle size effect of Pt on the kinetics of HOR, i.e., the exchange current density j(0) decreases with the increased dispersion (i.e. decreased mean particle size). A maximum mass activity of Pt for the HOR is found at particle sizes of 3-3.5 nm. The observed particle size effect is interpreted in terms of the size dependent distribution of surface atoms on the facets and edges, which is implied by the voltammetric responses of Pt/C catalysts with differently sized Pt particles. The accompanied decrease in the HOR activity with the increase in the edge atom fraction suggests that the edge atoms on the surface of Pt nanoparticles are less active for the HOR than those on the facets.

This review discusses optimization methods for LiFePO4from the extent of electron and Li+migration and proposes two future optimization approaches.

Stimuli-responsive polymeric micelles via click chemistry are divided into six major sections (temperature, light, ultrasound, pH, enzymes, and redox).